#12923: MultiParamTypeClasses + ExtendedDefaultRules -------------------------------------+------------------------------------- Reporter: amindfv | Owner: Type: feature request | Status: patch Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2816 Wiki Page: | -------------------------------------+------------------------------------- Comment (by amindfv): By the way, to get the current code to work we need to add: ` {-# LANGUAGE KindSignatures #-} ` and ` data A (b :: Bool) = A deriving Show ` to testsuite/tests/typecheck/should_compile/T12923.hs and ` import Kind ` to compiler/typecheck/TcSimplify.hs It does regress for Foldable at the moment, as Simon predicted, but in the test case I provided it does in fact work, beautifully! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12923#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler